SUSTAINABILITY
DEBRA KNAPKE
Stayin ’ Alive : Plant Strategies
Do plants have their own underground internet ?
Consider the plight of the plant : It is immobile , at least to the extent that it can ’ t pick up its roots and move to another location . A plant cannot talk , go in search of food or run away from predators .
In order to build sustainable landscapes , we must understand how a plant sustains itself . Without that knowledge , we will continue to create gardens and landscapes that rely on the overuse of precious natural resources and synthetic inputs to survive .
“ Plants breathe without lungs , digest without a stomach , see and hear without eyes and ears and think without a brain ,” said Stefano Mancuso , co-author of Brilliant Green and director of the International Laboratory of Plant Neurobiology in Florence , Italy . Plants do all the things that animals do to survive , but they do them differently . It is those very differences that help plants to thrive in a world where most other organisms consider plants to be food .
A PLANT CANNOT TALK
In a recent lecture at Ohio State University , Mancuso demonstrated how plant roots make sounds . He classifies these as clicks and admits that we don ’ t yet know how plants produce these sounds , but research indicates that they are perceived by other plants [ Gagliano , M ., Mancuso , S . and Robert , D . “ Towards Understanding Plant Bioacoustics .” Trends in Plant Science 17 , no . 6 ( 2012 ): 323-25 ].
Other researchers are also exploring plant communication strategies — how plants “ talk .” Suzanne Simard , a professor at the University of British Columbia ’ s Department of Forestry and Conservation Sciences , has spent more than 30 years researching the exchange of information or nutrients among different species of trees . In her TED Talk on July 29 , 2016 , she presented her case for a “ massive underground communication network ” among forest species . In one study , she used two isotopes of carbon dioxide and a Geiger counter to show that birch and Douglas fir trees
The above-ground network of this tree ’ s roots provides only a glimpse of the complex system that lies below .
exchange these different carbon compounds via their roots , aided by mycorrhizal fungi . In further studies she documented that the trees communicate “… not only in the language of carbon , but also nitrogen and phosphorus and water .”
Simard also found seasonal differences in these nutrient exchanges . For instance , in summer , birches send minerals to Douglas firs , while in winter the exchange is reversed . This is differential communication based on sensed need .
A PLANT CANNOT SEARCH FOR FOOD
A technical distinction needs to be made here . Plants make their own food ( carbohydrates and sugars ) through the process of photosynthesis . But for the purpose of this article , food refers to the nutrients that a plant takes up from soil , decomposing materials and fertilizers : nitrogen , potassium , phosphorus , other macro- and micro-nutrients and trace elements .
Animals can move to different locations to look for food . They can wait , pounce and then consume . The only plants that have evolved the ability to wait and pounce are carnivorous plants , which have adapted to absorbing some nutrients by digesting the soft parts of animal bodies . But the vast majority of plant species have had to make some deals .
As noted above , mycorrhizae have become the communication pathway between plants in the forest . While we do not truly know the percentage of plant species that have relationships with mycorrhizae , the most recent estimates are
© PHOTO COURTESY DEBRA KNAPKE
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